1. Field of the Invention:
The invention in general relates to electro-acoustic transducers, and in particular to an underwater hydrophone.
2. Description of the Prior Art:
Hydrophones, particularly those used in an anti-submarine warfare (ASW) application must be designed to exhibit a high sensitivity so that relatively low amplitude target signals will not be hidden by the electrical noise normally generated by the signal processing circuitry provided. For a typical ASW application, thousands of hydrophones may be utilized in a particular array and the hydrophones are connected to the signal processing circuitry via respective cables. Each of the hydrophones of the array must exhibit a relatively high capacitance to overcome the connecting cable capacitance without signal loss and present a low impedance source to the preamplifier utilized in the signal processing circuitry.
Of particular concern is electromagnetic interference (EMI) which can actually generate a signal on the output leads of the hydrophone and which signal may be displayed as a target, when in fact no target exists.
The hydrophone of the present invention is of a construction which exhibits high sensitivity and high capacitance in an arrangement which virtually eliminates the effects of EMI. This is accomplished in a hydrophone which is of relatively low cost and rugged so as to withstand the effects of possible nearby explosive shocks in an ASW environment.